They’re the Thomases: Bill (Michael Park), his wife Mia (Betsy Brandt), teen firebrand Alison (West Duchovny) and her awkward younger sister Claire (Kenlee Anaya Townsend). In the past, a well-to-do family arrives for vacation on Saint X, a Caribbean island loosely based on Aruba. The show splits its focus between a pair of storylines 20 years apart. But those who visit “Saint X” expecting a more straightforward narrative might lose interest before it reveals its charms. Those who prepared for the bait-and-switch by reading the novel will take to the series just fine, as will anyone weary enough of mysteries that they’ve given up attachment to the final reveal. That’s all the more disappointing because of how effective it is as a psychological thriller and a character study. The show also feints at a proper whodunnit, then builds to a nuanced, if anticlimactic conclusion, and all at a lazy river’s pace. Hulu’s series adaptation of “Saint X” hews closely to its source material, which winds up being as much a curse as a gift. It’s a meditation on trauma, shot through with social commentary and disguised as a nondescript “imperiled woman” beach read. But the story isn’t really about what happened, it’s about the grief, recrimination and obsession that consumes the survivors over time. Yes, the book slowly unfurls the details behind her untimely demise.

The body of a young American girl washes ashore in those tropical tides, and because her death incites the story, “Saint X” initially cuts the figure of a thriller.

“ Saint X,” Alexis Schaitkin’s acclaimed 2020 novel, has roiling depth beneath its placid surface, much like the pristine waters of the Caribbean island where it takes place.

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